Hot-air system for blast-furnaces.



PATENTED SEPT. 4, 1906.

T. KIDDIE. HOT AIR SYSTEM FOR BLAST FURNACES.

APPLICATION FILED SEPT. 30. 1905v 2 SHEETS-SHEET 1f INVENTOB Tim/210 5 Jfui'cZw.

BY Q 4' WITNESSES: i??? ATTORNEY- :rxn: ca, uusumormv p c PATENTED SEPT. 4, 1906.

T. KIDDIE HOT AIR SYSTEM FOR BLAST FURNACES.

APPLICATION FILED SEPT. 30. 1905.

2 SHEETS-SHEET 2.

v INVENTOR Thomas meld/e WITNESSES.

In NORRIS PETERS cc., wnsnmcrou, n. c.

THOMAS KIDDIE, OF LADYSMITH, CANADA.

- HOT-AIR SYSTEM FOR BLAST-FURNACES.

Specification of Letters Patent.

Patented Sept. 4, 1906.

Application filed September 30,1905. Serial No- 280,772.

To all 1071 0112, it ntay concern.-

Be it known that I, THOMAS KIDDIE, a citizen of the Dominion of Canada, residing at the city of Ladysmith, in the Province of British Columbia, Canada, have invented a new and useful Improvement in Hot-Air Systems for Blast-Furnaces, of which the fol lowing is a specification.

My invention relates to a hot-blast system particularly designed for application to blast or similar furnaces to effect the heating of the air from the blower by bringing it in contact with the heat of the waste gases from the furnace.

In smelting, the heating of the blast not only effects a more complete combustion of the fuel, but enables more satisfactory smelting results to be attained, as the oxidation of the sulfur, copper, iron, zinc, &c., is effected and the amount of raw ore used in the charge to produce a given grade of matte maybe materially increased. Further, by the more complete oxidation of the sulfur, iron, &c., the preliminary roasting of some ores may be dispensed with and the sulfur and iron oxidized in the furnace itself and their heat values utilized. With a view to obtaining these advantages from the waste heat of the furnace my efforts have been directed to expose the air-blast very fully to the heat of the waste gases in the flues and that in a gradual manner, exposing it first to the heat of the dust-chamber or the flue farther from the furnace and thereafter to the greater heat of the direct gases close to the furnace. By this means I not only impart a high temperature to the blast, by which alone I am enabled to derive full economy of fuel and advantageous results in smelting, but by the long exposure and gradual elevation of temperature the air-tube and jacketed linings last longer, as they are not exposed to extremes of temperature on opposite sides of the sheets of metal of which they are constructed. My system is thus in contradistinction to the short travel at high temperatures in cast-iron pipes, as in the ordinary hot-blast stove. A further economy in the utilization of the waste heat of the furnace is effected by decreasing the velocity of the gases through the flues and dust-chamber to the minimum by introducing a damper in the furnace-stack, by which means also the amount of cold air drawn in at the feed-doors is correspondingly reduced and a more complete settling of the particles of flue-dust is insured.

My invention is fully described in the fol lowing specification and illustrated in the drawings which accompany it, in which Figure 1 is a general plan showing the application of my system to an existing blastfurnace having a separate flue dust-chamber; Fig. 2, a similar view showing a modified arrangement appropriate to an installation of several furnaces; Fig. 3, a vertical section on the line A A in Fig. 1 Fig. 1, a cross-section of the jacketed flue leading from the blastfurnace to the dust-chamber; Fig. 5, a crosssection, to an enlarged scale,of the heat-absorption pipes in the flue dust-chamber Fig. 6, a side elevation showing a means for supporting and providing for the expansion of the absorption-pipes in the flue dust-chamber.

On referring to Figs. 1 and 3, 2 represents the blastfurnace, and 3 the bustle-pipes, from which the twyer-pipes 4 deliver the blast to the furnace. From the top of the furnace 2 a jacketed flue 5 conveys the furnace-gases to the dust-chamber 20.

In cross-section the flue 5 is preferably shaped as drawn in Fig. 4, the top and sides being inclosed by a plate 6, carried around and outwardly flanged, as at 7, to be riveted to corresponding outward flanges on the cover-plate 9, which cover-plate incloses an airspace 10 between it and the lining-plate 6, through which the air of the blast is passed on its way to the furnace-twyers in a manner to be described later. The bottom of the flue is formed of a trough-shaped plate 8, laterally flanged to rest on the girders 11 and form seats on which the flanged oint of the fluelining and its cover-plate rest. The cover-plate 9 extends beyond the ends 12 of the flue 5 and by means of end plates 13 jackets these ends with air-spaces 14 and 15 which are in connection with the air-space 10 which jackets the flue. The space 14 at the furnace end of the flue 5 is connected by down-pipes 16 to the bustle-pipes 3 on each side, and the space 15 at the opposite end is connected by a shallow flap-pipe 17 in the downtake 21, which delivers the furnacegases from the flue 5 to the flue dust-chant ber 20. The flap-pipe 17 is connected in the flue dust-chamber to the absorption-pipe 18, I

to be described later.

The air for the blast is delivered through the pipe 25, and a connection 26, furnished IIO with a stop-valve, will permit the air to be delivered direct to the bustle-pipes when for any reason such delivery may be found necessary, valves being also provided on the down-pipes 16. The blast-delivery pipe 25 is connected by a flattened pipe 27 to the absorption-pipe 18, before referred to, in the flue-dust chamber 20. This absorption-pipe extends along one side of the chamber to- Ward the chimney and returning along the other side is connected by the pipes 17 to the air-jackets of the flue 5. The absorptionpipe 18 is made of thin sheet metal and is in cross-section laterally narrow and vertically deep, the upper side 18 being formed as an inverted V to prevent any considerable settlement of flue-dust upon it and the under side rounded for convenience of manufac ture. It may be supported within the dustchamber in any appropriate manner that will provide facility for its expansion under heat, butis preferably suspended from the roof 30 of the flue-dust chamber by means of rollers 31, tracks 32, and hangers 33, somewhat in the manner illustrated in the righthand side of Fig. 5 and in Fig. 6. The flat sides of the pipe may be reinforced to enable them to Withstand without distention the internal pressure of the blast. On the righthand side of Fig. 5 such reinforcement is attained by longitudinal bars 84 on each side and stay-bolts 35 between; but the particular manner in which this is done is not material to this application.

The course of the blast air is as follows: From the delivery-pipe 25 it passes through the connection 27 to the absorption-pipe 18 in the flue dust-chamber, where it is exposed very completely to the heated gases therein. The air then passes up the flat pipe 17 in the downtake 21 to the jacket-space 15 and along the flue-jacket 10 to the space 14, and thence down the pipes 16 to the bustle-pipes. It will thus be seen that the air is gradually heated in its progress to the furnace, being first exposed to the less highly-heated gases in the dust-chamber and later, just before discharge through the twyers, to the direct heat of the furnace. All pipes and coverplates where exposed to the external air are protected by a covering of heat-non-conducting material to prevent loss of heat by radiation. Under these circumstances no great extremes exist on opposite sides of the plates of which the pipes and flue-lining are composed, and the life of the material of which these parts are made is thereby length ened. This is an important feature, as is evidenced by the short life of hot-air stoves at present in use in which a series of air-pipes are exposed to the extreme heat of the furnace-gases close to the furnace itself. These shallow flat absorption-pipes in the flue dustchamber offer an ample heating-surface in proportion to the cross-section area of the pipes, and their design is such that every opportunity is offered for endwise expansion by the heat of the flue, so that no straining of their structure takes place. WVhere a series of blast-furnaces are installed, it may be found convenient to connect them to one flue dust-chamber, as illustrated in plan in Fig. 2, when by extending the flue 5 the absorptionpipe 18 in the flue dust-chamber may be dispensed with altogether and the blast-pipe 25 connected direct to the jacket-space of the flue 5. The form of the flue 5 and its inclosing air-jacket is designed to accommodate itself to expansion and contraction due to variation of temperature and to the lateral extension due to the blast-pressure within the jacket-space.

Having now particularly described the nature of my said invention and the manner of its operation, I declare that what I claim as new, and desire to be protected in by Letters Patent, is-

1. In a device of the class described the combination with a blast-furnace flue or dust-chamber, of a thin metal pipe extending lengthwise therein, such pipe having in crosssection a width relatively less than its depth and a downwardly-sloped upper side, means providing for the longtudinal expansion and contraction of the pipe, means for admitting the air of the blast into the pipe at one end, and means for delivering the heated air to the furnace from the other end.

2. In a device of the class described; the combination with a furnace-flue or dustchamber, of a laterally-flattened thin metal pipe extending along one side toward the chimney and returning along the other, means providing for .the endwise expansion and contraction of the pipe, means for admitting the air of the blast into the pipe at one end and means for delivering the heated air from the other end to the furnace.

3. In a device of the class described, the combination with a flue dust-chamber, of an air-jacketed flue delivering the products of combustion from the blast-furnace to the dust-chamber, means for introducing the air of the blast to the flue-jacket space at the end of the flue farther from the furnace and means for delivering the heated air to the furnace-twyers.

4. In a device of the class described, a flue extending horizontally from the furnace to the flue dust-chamber,- such flue having a thin metal lining extending round the top and sides and a trough-shaped bottom, an outer casing inclosing the top and sides and preserving an air-jacket space between it and the lining, means for introducing the air of the blast into the jacket-space at the end farther from the furnace, and means for delivering the heated air from the end adjacent to the furnace to the twyers thereof.

5. In a device of the class described, a horizontal flue extending from the top of the furnace to the flue dust-chamber such flue being composed of a thin lining-plate inclosing the top and sides, the lower edges of the sides being outwardly flanged to be riveted to similar flanges on a casing-plate inclosing a jacket air-space surrounding the top and side lining, a trough-shaped bottom plate having laterally-projecting flanges on which the flanges of the lining and its casing are designed to rest means for introducing the air of the blast to the jacket-space of the flue at the end farther from the furnace and means for delivering the heated air from the other end to the twyers of the furnace.

6. In a device of the class described, a flue dust-chamber, a horizontal air-jacketed thin metal flue extending from the top of the furnace to the flue dust-chamber, a thin metal pipe extending along one side of the flue dust chamber and back along the other, means for admitting the air of the blast to one end of the pipe in flue dustchamber, means for connecting the other end of said pipe to the airjacket of the horizontalflue at the adjacent end and means for delivering the heated air to the furnace-twyers from the fluejacket space adjacent thereto.

. 7. In a device of the class described, a flue dust-chamber, a horizontal air-jacketed thin metal flue extending from the top of the furnace toward the flue dust-chamber thereof situated at a lower level, a downtake connectingsaid flue to the dust-chamber, a thin flat pipe of sheet metal extending along one side of the dust-chamber and returning along the other, a similar thin flat pipe connecting .one end of said pipe through the undertake to the jacket-space of the horizontal flue, means for delivering the air of the blast to the other end of the dust-chamber pipe and means for delivering the heated air to the twyers of the furnace from the end adjacent to the horizontal flue-jacket.

In testimony whereof I have signed my 45 name to this specification in the presence of two subscribing witnesses.

THOMAS KIDDIE.

Witnesses:

FRED PETERS, A. J. Ki'r'rsro. 

